debug-a-silent-failure

A troubleshooting guide for failures where something did not happen and produced no error, alert, or useful log.

In plain words
What is it for?
Use it when a job, sync, report, log, or configuration change has no visible effect and nobody knows whether it ran or failed.
Why use it?
It treats the missing result as evidence and helps find the point where the expected action or warning disappeared.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/everywan-dev/claude-code-engineering/debug-a-silent-failure
Any agent
npx skills add everywan-dev/claude-code-engineering --skill debug-a-silent-failure
Clone the repo
git clone --depth 1 https://github.com/everywan-dev/claude-code-engineering

Made for: Claude Code, Codex.

Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,699 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00048 $0.01699
Opus 5 $0.00024 $0.00849
Sonnet 5 $0.00010 $0.00340
Haiku 4.5 $0.00005 $0.00170

Measured 2d ago against content hash 05494d1c56a5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debug-a-silent-failure scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/debug-a-silent-failure/SKILL.md · 154 lines

How it starts

The opening of the file, as written. The whole thing — 154 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debug a silent failure

Most outages announce themselves. The expensive ones do not.

The signature is always the same shape: the thing that should have happened did not happen, and no layer said anything. No stack trace, no non-zero exit, no alert. Just an absence — and absence does not page anyone.

🔴 In this class of failure, the silence IS the symptom. Stop waiting for an error to appear. Start asking which component should have complained, and why it did not.

When to use this

  • "It should be running" and it is not
  • A change was applied and had no visible effect
  • A log stopped — not errors, everything
  • A job, a report, a sync did not produce output and nothing failed
  • Something was broken for days and nobody noticed
  • A count is zero and nobody knows if zero is correct

The procedure

1. State the missing event precisely. "The nightly export did not appear." Not "exports are broken". You are about to walk a chain, and you need to know what you are looking for at each link.

2. Walk the chain backwards, from the missing output to the trigger. At each link ask two questions:

  • Did this link run at all?
  • If it ran and failed, would anything have recorded that?

The second question is the one that finds it. Silent failures live at the link where the answer is no.

3. Look for the layer that swallows. Something is converting a failure into a non-event. Usual suspects, in order of how often they are the answer:

Swallower What it turns into silence
A success exit code on a failed operation The supervisor sees a clean finish and does nothing
A restart policy scoped to failures only A process exiting cleanly is never brought back
A cache in front of the broken thing Health checks keep passing off stale content
A transformation applied in the wrong order The later step matches nothing and reports success
An event that never crosses a boundary One node acts, the others never hear
Configuration that produces zero work Nothing runs, nothing fails, nothing is reported

Read the full file on GitHub · 154 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 154 lines · 48 tokens per session scan A 05494d1c56a5

Subscribe to this mod's changes

debug-a-silent-failure is a skill published in the GitHub repository everywan-dev/claude-code-engineering (2 stars, last pushed 13d ago), licensed Apache-2.0. It adds 48 tokens to every session and 1,699 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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